Hi, Do I need to commit my money for 90 days in order to get the 90 day t-bill rate? What happens if I want out after 30 days? Thanks.
No, you can buy and sell bills (obviously, if your broker allows this)... Just be aware of the bid/offer.
The actual rate you'll get will be determined by the difference between your entry and exit prices. To be certain of getting the 90 day t-bill rate, you'll need to hold for the 90 days. Holding for less will mean you can't be certain of the rate; it may be more, or may be less ... this will depend soley on the price you get when you exit.
I understand. I'm backtesting a market timing strategy back to the 1970's where in a given month I either hold a security or stay in cash. Can I assume the the return on cash will be the closest 90 day t-bill rate? Or should I assume the rate times 2/3 or 1/2? The 30 day t-bill rates data doesn't go back far enough.
It's fair to assume you get the current t-bill yield (obv, that's always quoted on an annualized basis).